Shopping wins when
- Your catalogue is large and varied — the feed covers ground no keyword list could.
- Price is competitive, because it is visible before the click.
- Buyers search by product type rather than brand.
Search wins when
- Merchant Center is blocked — Shopping simply is not available.
- Your catalogue is small, so keyword coverage is achievable and controllable.
- Intent is expressed in language, not in product names — problems, occasions, specifications.
In practice
Most accounts run both, with Search built first because it produces cleaner data faster and keeps working when the feed does not.